Card Set Information

2012-09-24 21:42:18
Geo Technology

Exam 1
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  1. Major Components of a Map
    • Scale bar
    • legend
    • North Arrow
    • Title
    • Discription
    • Source
    • Locator Map
    • Border
    • Credit
  2. Map Geometry 
    Symbols occupy more space than they generally take up based on the scale

    Linear widths, sometimes rivers are lines on a map other times they are polygons (question of scale and what is the real width of the river)

    Same is true for roads 
  3. Elementary Geometric Operations (Linear Features) 
  4. Elementary Geometric Operations
    (Point Features) 
  5. Elementary Geometrick Operations
    (Area Features)
  6. Map Symbology (NPS)
  7. Symbol (USGS)
  8. Meridian
    A plane that passes through the center of the Earth
  9. For reference in projection terms a meridian passes through the poles
  10. Since all are equal a prime meridian had to be selected
  11. Longitude lines of the Earth’s graticule 
  12. Parallel
    Lines placed at right angles to the meridians
  13. The equator is a parallel and is the main reference point for projections
  14. Latitude lines of the Earth’s graticule 
  15. Coordinate System
    Global systems

    – Most commonly used latitude and longitude

    • • Reno, NV
    • – Latitude 39° 30’ 30” North
    • – Longitude -119° 48’ 30” West

    • Degrees, Minutes, Seconds (dms)

    • • Decimal Degrees (dd)
    • – Latitude 39.508333333
    • – Longitude -119.80833333

    • • Conversion to decimal degrees
    • – decimal deg. = degrees + (minutes / 60) + (seconds / 3600) 
  16. Spheroid
    A three-dimensional shape obtained by rotating an ellipse about its minor axis, with dimensions that either approximate the earth as a whole, or with a part that approximates the corresponding portion of the geoid.
  17. The shape and size of a coordinate system is defined by the spheroid
  18. Smaller scale systems can assume sphere shape for earth (more on that later) 
  19. Most created with a specific region in mind
  20. Geoid
    Earth not a true ellipse or sphere, but has an irregular shape. This shape is called a geoid.
  21. Think in terms of the highest mountain peak and the lowest ocean valley
  22. Conical Map Projections
    • Albers equal-area
    • Conical can also be good for distances
    • Scale and shape distorted 
  23. Cylindrical 
    • Distortion different close to poles    
    • Meridians are now the important points
    • UTM zones run north-south with a central meridian 
  24. Azimuthal
    • Projections onto a plane
    • Good for direction
    • Map distances can be computed by a function